A terminal end of an optical fiber cable used for various communications is provided with an optical connector for use in relay or connection to other apparatuses. The optical connector includes a cylindrical ferrule of which an optical fiber is inserted into an inner circumferential part, and a plug housing which holds the ferrule and is connected and fixed to other apparatuses or an adaptor for relay.
In the optical connector, if an end face of the ferrule (including the optical fiber) which is a connection portion is scratched or stained, the communication quality of the optical fiber deteriorates. Thus, when an optical fiber cable is connected, an end face inspection apparatus which inspects a state of an end face of a ferrule of a formed optical connector is used.
The end face inspection apparatus captures an image of the end face of the ferrule of the optical connector with an image sensor, and enlarges and observes the captured image so as to find a scratch or a stain.
Non-Patent Document 1 discloses that an operator manually finely adjusts a focus of an image captured with an image sensor, and a focused image is acquired.
However, in such an end face inspection apparatus, an operator is required to manually perform fine adjustment for focusing, and thus time for fine adjustment is taken. The operator is required to perform an operation for acquiring a focused image while viewing an image displayed on a display unit of the end face inspection apparatus, and thus it takes time to acquire a focused image.
In order to cope with such a problem, Patent Document 1 has proposed a technique in which an end face of a ferrule of an optical connector is focused through automatic focusing, and then captured image data is subject to image processing.